The Sierra Club and a group called Protect Our Aquifer were expected to file a lawsuit Wednesday, Feb. 1, in Chancery Court, challenging new water wells the Tennessee Valley Authority is planning to dig at its new Allen Combined Cycle Plant in southwest Memphis.

The lawsuit is an appeal of a decision by the Shelby County Groundwater Quality Control Board that allows TVA to complete its plan to drill five wells into the aquifer to supply water that would be used to cool the natural gas-fired power plant.

TVA is building the natural gas plant to replace the coal-fired Allen Fossil Plant nearby.

The groundwater quality board affirmed in its earlier decision that TVA had followed all of the existing rules and that there was no reason to deny the permit.

The lawsuit contends the hearing was “procedurally flawed and prevented the appellants from presenting important expert evidence,” according to the plaintiffs’ attorney, Webb Brewer.

The original plan called for using treated wastewater, or so-called “gray water,” to cool the new plant. But TVA later decided to drill its own wells into the aquifer, citing its concerns that material in the wastewater might damage the machinery.

The Sierra Club contends not enough is known about existing breaches of the clay barrier protecting the aquifer and that new wells could leak contaminated groundwater into the aquifer.

TVA board chairman Lynn Evans of Memphis has said the authority has obeyed all regulations with the new wells and that there is no risk to the aquifer, which provides the city’s water supply. She also has said the decision to drill wells came at a lower cost to the TVA than buying the water from Memphis Light, Gas and Water Division.

MLGW officials have said their preference would be for TVA to buy the water from the utility without digging its own wells.